Joe Root has shown an ability to adapt to any given match situation in his brief international career. The brief for England on a Lord's Saturday was to take the heat out of the game and bat Australia into oblivion. And so Root did. Around the time that Australia were conscious only of the fact that there was no hope, he raised his bat to celebrate a maiden Test hundred as an England opener.

"Grind them down, Joe" would have been the message and so Joe did. If an occasional back-foot drive was reminiscent of Michael Vaughan, in the first two sessions there was a touch of Geoffrey Boycott in his fastidiousness.

The benefits then accrued in a rush as England, who made 141 off 58 overs in the first two sessions, piled up a further 162 in 32 overs after tea. Root's well-structured 97 blossomed into an unbeaten 178. England closed the third day with a lead of 566. No side has chased that to win in the fourth innings in the history of first-class cricket. Australia were not thinking about it. They were just thinking about bed.

Root took five-and-three-quarter hours for his hundred, poring over it so intently that he might have replaced his helmet with gown and mortar board. He, too, has been in his year of graduation, and now he has emerged with honours, stilling the discussion surrounding his supplanting of Nick Compton as opener at the start of the Investec Ashes series.

If he had been caught on Friday evening on 8, when wicketkeeper, Brad Haddin, and first slip Michael Clarke left the catch to each other, life might have felt different. Instead, once his hundred had been achieved and with England looking for impetus in the final session, he gambolled along, his inventiveness at its height, particularly against the left-arm spin of Ashton Agar.

Australia's quicks had shouldered a heavy workload over the past 11 days and, with Root's hundred settled eight balls after the new ball was available, Clarke chose not to take it to spare his quicks further punishment. It became an increasingly perplexing call. In 20 overs after tea, England added 111, a carefree 153-run stand between Root and Ian Bell ending when Bell, on 74, hauled a long hop from Steve Smith to midwicket.

Australia were aggrieved that Bell, when only 3, had not fallen to a catch by Smith at gully when Ryan Harris forced the edge. The umpires handed it to the TV umpire, Tony Hill, to determine if the ball had carried. It was a tough decision, as there was the vaguest suspicion that the ball might have burst through Smith's hands, but the foreshortening of a TV lens notoriously can make good catches seem illegal and it was probably out.

If Clarke was to bowl spinners so avidly, he could have done with a proven one. As Agar and Smith bowled in tandem, it felt like an educative process, the teaming up of a fledgling slow left-armer and a legspinner who has largely shelved the craft while putting more emphasis on his batting. There is nothing wrong with education. It just felt odd that it should be taking place in the middle of an Ashes series.

Australia's three-wicket burst at the close of the second day had lifted heartbeats, but as the match progressed past its mid-point, they were searching for a pulse. In the first two sessions, they took only one wicket, that of the nightwatchman, Tim Bresnan, who flat-batted a pull against James Pattinson to midwicket, a reward for Pattinson, who had made the previous ball rear awkwardly.

Bresnan's batting and bowling statistics have declined markedly since his elbow operation, but he is having a decent Test. Two successive boundaries against Siddle possessed some fortune - an edge in front of Phil Hughes at third slip and a leg-side clip - but Australia were unable to maintain the threat.

Australia's collapse to 128 all out on the second day had been inexplicable, but the quick loss of three England wickets to the new ball had left the slightest unease. The ball was turning, and would turn more, and there was occasional uneven bounce, but nothing untoward. Root's response was faultless.

Only in the final session as the pace of the pitch lessened and the bounce of the ball became more erratic did it become a more challenging surface for batting and by then England's batsman were in the mood to disregard it.

England's nightwatchman tactics do not please everybody, but twice in this Test their logic has been hard to fault. In the first innings, the use of James Anderson as a nightwatchman to protect Stuart Broad, a No . 9, was felt by some to be risible, but Broad and Graeme Swann embarked upon a crowd-pleasing last-wicket stand which lifted England's mood.

As Root walked onto the Lord's outfield on Saturday morning, it seemed shrewd that this time the nightwatchman should be Bresnan, a fellow Yorkshireman able to offer a few words of counsel if his mood ran away itself, and with enough credentials with the bat to have the chance of making a contribution of his own.

England settled carefully. It was six overs before Root risked a cover drive against James Pattinson, not entirely securely. Pattinson, who has struggled to settle to the vagaries of the Lord's slope, had a much more solid day. But Root met everything judiciously. Australia, recognising his strength on the back foot, sought to draw him forward, but two easeful straight drives against Siddle had suggested by lunch that his weaknesses are merely comparative.

In the afternoon, he batted time. But he is a calculating batsman for one so young and he would have liked his hundred before tea. Clarke challenged him to do just that in the last over before the break when he introduced the legspin ofSmith. A cut boundary took him to 96, Agar dived at extra cover to prevent another boundary and he could only hack a full toss to mid-off. There had been no over with such incident all day.

Back out again he came after tea, on 97. Shane Watson made one leap, Agar made one creep out of the footholds. Smith made a great diving stop at gully. Root grinned at the fun of it all. Then he cut Agar to reach his hundred. In the penultimate over, he twice heaved Smith over midwicket for six, any inhibitions of the morning long since cast aside.

Soon after his hundred, a member of the MCC groundstaff brought him a drink. It was his brother, Billy, not a bad player himself. They shook hands and then broke into a quick hug. Life is going your way when the family can stroll on to congratulate you.

After enduring a tricky start to his Manchester United career, perhaps it is fair that Marcos Rojo celebrated so boisterously as he watched his first professional club Estudiantes beat fierce rivals Gimnasia